Telephone-exchange system



R. S.Y B'LEY.

TELEPHONE EXCHANGE SYSTEM.'

APPL ICATION FILED JAN. 7 1920.

melmaY ont. 31, 1922.

/Hvenoh Hand Sfephen 25 a//e by MQ a trunk such as T has been tested andfound idle, ringing current will be sent over the conductors 10, l1 ofthe trunk leading to the inanual exchange to energize a relay l2thereat. The circuit therefor is as follows: ground, wiper 1li in itsthird position, brush `90, terminal conductor 82, tip spring and contactof jack 15, winding of relay 12, contact and ring spring of jack15,*conductor 10, Contact 83, brush 81, wiper 16 and its third contact,winding of ringing cutoff relay 17, front contact and armature of relay18 which is energized in the third position of the side switch wipers,to a source of ringng current 19. Attraction oit' the armature or' relay12 causes a signal 2G to be dis played indicating to the operator that acall has arrived.

.The operator thereupon inserts plug 25 into jack cutting off relay 12to extinguish lamp and operating relay 26 of the cord circut B, thecircuit therefor being from grounded battery, resistance 13, sleeves ofjack 15 and plug 25, winding of relay 26 to ground. Relay 26 attractsits armatures thus placing an alternatingcurrent bridge across thetalking conductors of the cord circuit B.

The insertion of plug in ack 15 transfers the circuit itor ringingcurrent to relayy 50 oi said bridge over the following path: ground,third contact and wiper 14;,brush 90', contact 82, conductor 11, tips ofjack 15 and plug 25, conductor 31, lefthand nor mal contacts of relay32, conductor 33, upper spring and normal contact of the answering cordringing key 80, conductor Bil, left-hand winding of retardation coil 36,inner rightarmature and make contact of relay 26, normal contact ofrelay 40, inner righthand armature `and back contact of relay 41,right-hand winding of ring-up relay 30, condenser 42, front contact andouter righthand armature of relay 26, right-hand winding of retardationcoil 3G, conductor 46, com tact and lower spring of the answering cordringing key 80, conductor e157, normal contacts oi the lett-hand innerarmature of reT lay 32, conductor 48, ring of plug 25, ring or jack 15,conduct-or 10, brush 83, contact 81, wiper 16 and thirdcontact, windingof relay 17, iront contact and armature of relay 18 to source of ringingcurrent 19. Re-

lay 30 locks up under control of key 50. TheA operator then actuates theylistening key 50, thus bridging her head-set across the talkingconductors oi the cord circuit B. Actuation of thel listening key opensthe locking circuit to: relay 30, and causes energizati'on of relay 10.which interrupts the alternating current bridge in the cord circuit Band substitutes therefor a direct current bridge resulting in thel sideswitch at theI connector switch moving from position 3 to 4 in thewell-known manner. `Relay -LO is energized over the following path:grounded battery, winding ci relay 40, outermost lower contacts oi? key50, back contact and lett-hand armature ot relay 41, and lower makecontacts of the right-hand inner armature ot relay 26 to ground. Relayl0 is held locked'up over its left-hand armature and front contact. Thealternating current bridge was interrupted at the normal con. tacts ontrelay 40 and the direct current bridge was established at the right-handarmature land alternate contact of relay 4:0.

The operator having ascertained the 'number of the desired line, plug 52is inserted into jack 53 and ringing key 55% is actuated to send ringingcurrent over --the line to substation C in the usual manner. insertionof plug 52 into ack 58 energized relay 54 thus disconnecting line relay56 from substation C and causing supervisory lamp to light over thefollowing path: grounded battery, lamp right-hand armature and backcontact of relay 41, sleeve of plug 52, sleeve otjack 53, winding ofrelay 54C to ground.

in response to the ringingsignal, the subscriber at substation C removesthe receiverV from the switchhook, whereupon relay 58 of the cordcircuit is energized by current from the line relay 5 of the connectorcircuit at the autom interchange flowing over the talking conductors oiCtrunk'l, cord-circuit and ythrough the loop of substation C. The windingof relay is of low resistance. and although there are other paths :torthe current from the automatir^` exchange through the winding ofretardation coil 86 and the shunt 59, sui'iicient current flows throughrelay to energize it, Upon energization, relay through its iront contactand arma# tur-e closes a circuit to energize relay 41 ifl'iicli, uponattracting its armatures, causes the cord supervisory lamp to beextinguished by interrupting the circuit for said lamp at its outerrightehand armature and back contact, and the control ci' 'the automaticswitch ling apparatus to be transterred vfrom the (ford circuit to thesubstation C by inter-u rupting the holding circuit 'tor relay 4i() atthe lett-hand armature and back contact ot relay 4:1. Talking currenttor substation C is supplied from relay 5 of the connector circuit overthe talking conductors of the trunk andcord circuit, through the relay58 and the shunt 59 thereof and thence over the talking conductors ofthe cord circuit B and the line leading tosubstaticn C. The relai;Y

5 in attracting its armature operates relay` 94 which locks itself toground at oid-normal switch 95. In attracting its lett armature,

relay 94: removes the control of the release of the switches from thesubscriber at substation i by shitting the battery connected to therightwinding of relay 91 to the front contact of relay it 'the conclusion ofconversation, the subscribers. restore the receiversfto the switchhooks.The replacement of the `receiver at station C releases relay 5 whichreleases re-` lay 91. Relay 91 releases slow relay 92. Theretractedcondition of the armatures of these latter relays closes thecircuit `of release magnet 93 which restores the connector. Theretraction of the right' armature of slow relay 92 removesr ground fromthe release wire 9G resulting in the release of the Vpreceding switchesin the well-known manner. rlhe restoration of the receiver to theswitchhook at station C' either before or after `the subscriber atstation A hangs up releases relay 58 since ciu'rent ceases to flowthrough this relay. Relay 5S in retract-ing i/tsfarmature opens thecircuit :for relay 411 which in reti-acting its armaturesrie-establishes the alternating current bridge `across the talkingconductors of the cord circuit so that should another` call Aarrive overthe trunk circuit T before the operator has withdrawn the plugs,subscriber C will not be signalled due to the energization of relay 30which responds to ringing current from the distant office and locks upthereby interrupting the continuity of the talking conductors leading tostation C. The ringing current is thus prevented from passing throughand signaling station C. Relay L,Ll in releasing also completes acircuit for supervisory signal indicating to the operator thatconversation has ceased.

If the trunk T is selected before disconn nection takes place,'relay 80will be energized thereby completing a circuit for signal 65. Thissignal serves to indicate to the operator that another callhas arrivedfrom the automatic exchange. The operator thereupon removes plug` 52from ack actuates listening key 50 and then proceeds as with anyincoming call.

lnthe foregoing, a description has been given of the operation `of cordcircuit B for completing an incoming call from an automatic exchange. Abrief description of the operation and use of the cord circuit forcompleting an outgoing call will now be given.

ln response to the removal of thereceiver from theswitchhook at stationC, line relay 56 and in `turn line signal 60 operate. The operator inanswering inserts plug 52 into jack 53 whereupon relay 54 operatesthereby cutting olf line relay 56 and eX- tinguishing linesignal 60.Supervisory relay 58 operates over a circuit including ground. backcontact and inner right-hand armature of relay 26, left-hand winding ofretardation kcoil 36, upper normal contacts of ringing key 54C, tips ofvplugs 52 andjack 53, the substation loop, rings of jack and plug 52,lower` normal conta-cts of ringing key 54h winding `of relay 58 andshunt 5t" thereof in parallel, outer vleft-hand armature andback contactof relayxBO7 righthand winding oiireta'rdation coil 36, outer right-handarmature and back contact ol relay 2G and grounded battery. Relay 58 inoperating' completes a circuit at its righthand armature and frontcontact for relay 4l. The operator then actuates listening key 50-andupon being informed by the calling subscriber that station A. at theautomatic exchange is desired, inserts plug 25 into jack l5. Relay 26then operates over the path previously traced.. Relay 26 in attractingits righthand armatures disconnects battery and ground from the talkingconductors and current fromthe iirst selector at the automatic `exchangeis substituted therefor over linder N which maintains relays 58 `and 4:1operated. The oper` `ator then actuates impulse sender S to transmitimpulses over 'the trunk T to the automatic exchange to set the selectorswitches and the connector thereat in accordance with the number desiredin the well known manner. f f

Impulse sender S is provided with a set of' contacts T0 which areactuated a numberl of timesin accordance with the digit dialed to setthe switches and with a set of contacts 7l which are closed when thedial is `in an olf-normal position. The contacts 7l are closed upon theinitial movement of the dial and remain closed during the entiremovement and until the `dial Vreturns to normal. lVhen sender S isactuated, con,-

tacts 7l are closed thereby completing a circuit for relay 32, saidcircuit including the uppermost contacts of key 50. Relay in operatingdisconnects the calling from thejanswering end ofthe cord circuit andconnects battery and ground to the talking conductors of the answeringend. After the last series of impulsesv have been sent, relay 32 1ndeenergimng renders the cord circuit continuous. Key 50 is then restoredto normal, whereupon talking current is fed to station C from theconnector at the autoA matic office in the well-known manner.

llpon completion of conversation, subscriber (l in restoring thereceiver to the switchhook opens the loopleading to the automaticexchange whereupon supervisory relay 58` deenergizes and the switches atthe automatic exchange are released in the usual manner. Relay 58 inretracting its armature opens the circuit for relai/141 whereuponring-up relay 30 is bridged across the talking conductors.

l Supervisory `lamp 55 lightsindicating to the operator lUO as beforementioned that a call exists on trunk T whereupon 4plug 52 willbe-removed and listening key operated to inquire from the callingsubscriber the number desired.

llVliat is claimed vis l. in a telephone system, a calling line and a.called line, means including automatic switches, ak trunk line and acord circuit tor interconnecting said lines, a bridge across said cordcircuit eliective until the response of the called subscriber forpreventing `said switches from releasing, and `means fcontrolled overthe calledy line tor opening said bridge.

` 2. lny a telephone ing line and a called line, means includingautomatic switches, a trunk line and a cord circuit for interconnectingsaid lines, an alternating and a direct current bridge for saidcordcircuitoperator controlled .means for removing said alternatingcurrent bridge andsubstituting therefor the direct current bridge, andmeans under the control of the called line 'tor removing said directcurrent bridge. y, c

In a telephone exchange system, a cali,- ing line, a called line, meansincluding anto-` lnatic switches and a cord circuit 'for intei-,connecting said lines, manual means in said cord circuit lior placing aholding bridge across the cord circuit until the called sub. scriberanswers, automatic means for removing said bridge .when said called lineanswers, and means for substituting a bridge at the called station. A

hln a telephone-system, a calling` line.l a called line, apcord circuit,means including automatic switches for rinterconnecting said lines oversaid cord circuit, a key in said cord circuit, a relay actuated inresponse tothe actuation oi' Said key, adapted to place a holding bridgeacross the cord circuit, a second relay in said cord circuit actuated inresponse to the answering of the called subscriber 'for disabling` saidholding bridge, and meL is tor substituting a holding bridge at thecalled station. l

lfu a telephone system,y two subscribers1 lines, a cord circuit, meansincluding autoniatic switching apparatus for establishing a connectionbetween said lines over said circuit, and for impressing alternatingcurrent on said. cord circuit, means controlled over one of said linesfor releasing the automatic switchingapparatus and for immediately7causing an alternating currentbridge to be connected across the talkingconductors of the cord circuit, and means controlled by'4 said bridgefor preventing alternating current from operating the bell at the calledstation,

' 6. ln a telephone system, two subscribers lines, cord circuit, meansincluding automatic switches for establishing a connection between saidlines over said cord circuit,

-and for impressing` exchange system, a call.

alternating current controlled on said cord circuit, means over thesubscribers lines for releasing i the automatic switches, a source otcurrent associated with said automatic switches -for supplying talkingcurrent for said lines, a relay associated with said cord circuitactuated by said source of current, an alternating current bridge norm(lly disconnected from said cord circuit means controlled'by saidv relayfor connecting said alternatingcurrent bridge to said cord circuit, andmeans controlled bysaid bridge for preventing alternating current fromoperating` the bell ot the called station.

7.111 a telephone exchange system, an automatic exchange, a manualexchange, two subscribersj lines, one terminating at each ot'saidexchanges, `a cord circuit at said manual exchange, means includingautomatic switches for establishing a connection. between said linesvover said cord circuit, means controlled over the subscribers lines forreleasing saidswitches, a source oi ringing current at said automaticexchange, a relay associated with said cord circuit responsive to theringing current adapted upon actuation to interrupt the continuityv otthe talking conductors leading to one oii'said lines, a locking circuitfor said'relay and -ineans tor opening said locking circuit.

8; In a telephone exchange system, a calling and a called line, a cordcircuit,\means including automatic switches for connecting said linesover said cord circuit, including a pair of talking conductors, means orsig'- naling said called line, a holding bridge in .said cord circuiteffective until the subscriber ot said called line answers, means fordisabling said holding bridge upon the response et the subscriber of thecalled line, means tor connecting an alternating current bridge acrossrthe talking conductors ot' lsaid cord circuit upon restoration of thereceiver to 'the switchhook at the station of the called subscriber, andmeans controlled by the re-A placement oif the receiver at thesubscriliers stations for releasing said switches 9. In a telephoneexchange system, two subscribersv lines, a station for each line, atrunk circuit, a cord. circuit, means includ- -ing automatic switchesfor establishing a connection between said lines over said trunk andsaid cord circuits, signaling responsive means associated with said cordcircuit normally disconnected therefrom and means for releasing said,switches land connectingy said signal responsive means to said cordcircuit when one of said subscribers restores the receiver to the,switchhook 10'. In a telephone evchange system,l in combination, atrunk circuit including automatic switches extending from a first to asecond ollice, a telephone line terminating at the second office, a cordcircuit thereat for llO connecting the trunk circuit with the telephoneline, means `cont-rolledover said line for releasiiig said automat-icswitches, relay in the cord circuit responsive to alternating current,said relay being disconnected from said cord circuit when the receiverof the telephone line is removed from the switchhook, and means forbridging said relay across the talking conductors of said cord circuitwhen the receiver is restored to the switchhook. y

11. ln a telephone exchange system, an automatic telephone exchange, amanual telephone exchange, means including a trunk circuit or extendinga call from said automatic to said manual exchange, a cord circuit torconnecting said trunk circuit to a called subscriber at said manualexchange, a ringing rela)v in said cord circuit actuated in response tothe sending of ringing current over said trunk circ-uit, a key in saidcord circuit adapted upon actuation to disconnect said ringing` relayand establish a holding bridge in said cord circuit, and means in saidcord circuit adapted to remove said holding bridge upon the response ofthe called subscriber, said means being arranged to again connect saidringing relay to said cord circuit upon restoration ot' the receiver tothe switchhook,

l2. In a manual telephone exchangma trunk circuit incoming from anautomatic exchange including automatic switches, terniinating in a jack,a cord circuit for extending a connection 'from said automatic exchangeto a called substation in said manual exchange, a holding bridge in saidcord circuit effective until said called substation answers, substitutebridge at the called station. closed upon the removal ot the receiverthereat for controlling the release ot said automatic switches, and analternating current bridge in said cord circuit effective when saidcalled substation has restored the receiver to the switchhook.

13. A telephone exchange system coml prising a manual telephoneexchange, a switchboard, telephone lines terminating therein, a trunkcircuit extending from said switchboard to an automatic exchange andincluding automatic switches thereat, a ringing relay in said cordcircuit normally disconnected therefrom adapted to open up the talkingconductors of the calling end of said cord circuit upon energization,manual and automatically controlled means for connecting said relay tosaid cord circuit, and means controlled by the subscriber :for releasingsaid switches.

141-. In a telephone exchange system, a trunk circuit extending from anautomatic to a manual exchange and including automatic switches, acalling subscribers line at said automatic exchange, a calledsubscribers line at said manual exchange, a cord circuit at said manual.exchange 'for connecting saidcalling with said called line, a holdingbridge in said cord circuit eiiective upon the response of the operatorto the call from the called subscriber, a. relay in said cordcircuitactuated in response to the removal ot the *receiver 4trom theswitchhook on the calledl subscribers line for disabling said holding'bridge, means for substituting a holding bridge at the` called station,and means controlled by the opening of the bridge forreleasing saidautomatic switches. 15. In a telephone system, an automatic oiiice, amanual ofiice, a cord circuit thereat, called lines terminating in jacksat said manual oliice, a trunk extending from said automatic oliicetosaid manual oliice and terminating in a jack thereat, a callingstation having a dial for setting the switches at the automatic othce topick out said trunk, a signal operated upon the selection of said trunk,a bridge across said cord circuit, a manual switch controlled by theoperator for causing the closure ot said bridge, means operated therebyfor transferring the control oi' the release ot said automatic switchesto said bridge, means controlled by the called party for closinganother' bridge at the called line to hold said switches set and foropening said itirst bridge, and means controlled by the called party foropening said latter bridge to release said automatic switches.

16. In a telephone system, an automatic office, a manual office, a cordcircuit thereat, called lines terminating in jacks at said manualoffice. a trunk extending from said automatic oliice to said manualoiiice and terminating in a j ack thereat, a calling station having adial for setting the switches at the automatic oliice to pick out saidtrunk, a signal associated with said trunk jack, means at said automaticoilice for impressing alternating current on said trunk to operate'saidsignal, an alternating current bridge adapted to be closed across saidcord circuit upon the insertion of the answering plug, a direct currentbridge, a key in said cord circuit for placing the same across said cordcircuit, means operated thereby for disconnecting said ringing current,and a relay operated by the response ot the called party for openingsaid direct current bridge and substituting a bridge at the calledstationto control the release of said automatic switchese y1'?. Intelephone system, a talking connection including a calling automaticsubstation, a trunk includingv automatic switches, a cord circuit and acalled manual station, means for impressing alternating current on thecord circuit from the automatic oliice, a bridge at the called stationfor controlling the release of said switches, and an alternating currentbridge at said cord circuit including a relay adapted to liov impressingalternating cuilent'on said cord Circuit to operate said relay, and alsignal in said Cordeircuit controlled by said relay. l0

n testimony whereof, I have signed my name to this specifica-tion this5th day of January, 1920. v

, RAND SBAILEY.

